The present invention relates to a fuel injector.
German Published Patent Application No. 198 49 210 has already disclosed a fuel injector for fuel injection systems of internal combustion engines which has a magnet coil, an armature that can be impinged upon by the magnet coil against a return spring in a linear stroke direction, and a valve needle that is joined to a valve-closure member. The armature is movable between a first stop joined to the valve needle that limits motion of the armature in the linear stroke direction, and a second stop joined to the valve needle that limits motion of the armature opposite to the linear stroke direction. A damping spring in the form of a cup spring is positioned between the second stop and the armature.
One of the disadvantages of the fuel injector known from German Published Patent Application No. 198 49 210 is that manufacturing and assembly complexity are increased because of at least one additional component. Another is that, for example because of skewed placement of the cup spring or manufacturing tolerances that occur during production, misalignment or jamming of the armature can occur during operation of the fuel injector. Extreme variations in armature travel and in the height of the pre-stroke gap occur as a consequence. Both factors can result in malfunctions during operation of the fuel injector.
The fuel injector according to the present invention has, in contrast, the advantage that a pre-stroke of the armature is adjustable, very accurately and with no damage to the components used, by way of a clamping sleeve that can be slid onto the valve needle and positioned as desired.
It is particularly advantageous that a lateral slit in the clamping sleeve makes possible easy installation by way of an elastic preload of the tubular component, the clamping force of the clamping sleeve being selectable, by way of its axial length, to match the weight of the armature.
The particular shape of the conical bevels of the clamping sleeve advantageously ensures that non-damaging installation is possible.
It is especially advantageous that production of the entire component can be accomplished quickly and economically, since the clamping sleeve and the spacer ring are easy to manufacture and no further components are required.